Blueprints for Taming the Climate Crisis

Image

A power plant near Meridian, Miss. The facility is the only commercial power plant in the country that plans to capture its own carbon emissions.CreditCreditGary Tramontina/Bloomberg News, via Getty Images

Here’s what your future will look like if we are to have a shot at preventing devastating climate change.

Within about 15 years every new car sold in the United States will be electric. In fact, by midcentury more than half of the American economy will run on electricity. Up to 60 percent of power might come from nuclear sources. And coal’s footprint will shrink drastically, perhaps even disappear from the power supply.

This course, created by a team of energy experts, was unveiled on Tuesday in a report for the United Nations that explores the technological paths available for the world’s 15 main economies to both maintain reasonable rates of growth and cut their carbon emissions enough by 2050 to prevent climatic havoc.

It offers a sobering conclusion. We might be able to pull it off. But it will take an overhaul of the way we use energy, and a huge investment in the development and deployment of new energy technologies. Significantly, it calls for an entirely different approach to international diplomacy on the issue of how to combat climate change.

“This will require a heroic cooperative effort,” said Jeffrey D. Sachs, the Columbia University economist who directs the Sustainable Development Solutions Network at the United Nations, which convened the multinational teams.

The teams, one in each of the 15 countries, looked at what would be necessary to keep the atmosphere from warming more than 2 degrees Celsius, 3.6 degrees Fahrenheit, above the preindustrial average of the late 19th century, a target that most of the world committed to at the climate summit meeting in Copenhagen five years ago. To do so, CO2 emissions from industry and energy use would have to fall to at most 1.6 tons a year for every person on the planet by midcentury.

That is less than a tenth of annual American emissions per person today and less than a third of the world average. And we haven’t quite figured out how to get from here to there.

The American team built several paths that would hit the target, using different mixes of nuclear power, renewable energy and fossil fuels with carbon capture and storage technology. So did the Russian team, aided by the expected shrinking of the Russian population.

But the Chinese team was stymied by the country’s vast heavy industry — its steel makers and cement plants, which use enormous amounts of energy. The best it could do was chart a path that took CO2 emissions to some 3.4 tons per person by midcentury. “We have shipped a lot of industry to China,” Mr. Sachs said. “Industry is hard to decarbonize.”

Over all, the teams built plausible technological paths to cut annual emissions across the 15 countries only to about 2.3 tons per person.

The analysis, however, offers solid ground for hope. The teams expect to improve on these paths in coming months. Faster deployment of some technologies than assumed could provide for deeper decarbonization in several countries. What’s more, likely changes in economic structure in coming decades — such as China’s expected shift away from heavy industry — could further shrink the carbon footprint.

Most important, the assessment offers an opportunity to end decades of inconsequential horse-trading over climate change and to start addressing the problem for real.

Five years since political leaders from countries around the world committed to do whatever it took to keep global temperatures from rising more than two degrees above the preindustrial average, no one had taken the trouble, until now, to evaluate how that might be achieved.

Lacking any understanding of the feasibility of the exercise, governments postured and jockeyed over which country should be responsible for what, offering as little as they could get away with in actual reductions in greenhouse gas emissions, whether the collective effort met the two-degree commitment or not.

“If governments don’t have any idea of what two degrees means in their countries, how can they commit to two degrees?” asked Guido Schmidt-Traub, executive director of the Sustainable Development Network.

The report commissioned by the United Nations could end the jockeying: to stick to the two-degree limit every country, rich and poor, must reduce annual CO2 emissions to 1.6 tons per person, whether it is responsible for a lot or a little of the climate change so far.

This is dictated not by fairness, but by our technological frontier. There is wiggle room for negotiation. China’s emissions from manufacturing would look smaller if they were allocated to consuming rather than producing countries. Still, we know of no feasible technology that would allow, say, the United States to have negative emissions in 2050 so India or China could emit more.

The new assessment also underscores the pointlessness of small, incremental emissions cuts. Under the path, the United States decarbonizes its energy supply at an average pace of almost 4 percent a year over the next four decades. That is more than 10 times faster than the Energy Information Administration’s forecast last year. China takes CO2 out of its energy about six times as fast as the E.I.A.’s forecast.

This is not achievable by going after low-hanging fruit, such as replacing coal with natural gas in power plants. Doing so could even be counterproductive, locking the country’s energy infrastructure into a high-carbon path.

Most important, perhaps, the new assessment suggests that deep decarbonization can be done without breaking any economy. Chinese incomes, for instance, are assumed to grow about 4.6 percent a year until midcentury.

The decarbonization paths rely on aggressive assumptions about our ability to deploy new technologies on a commercial scale economically. For instance, carbon capture and storage is supposed to be available starting in about 10 years. Second-generation biofuels are assumed to come into play by 2020. Hydrogen fuel cells and power storage technology are deployed starting around 2030.

But these technologies all exist today and seem reasonably scalable. The teams did not rely on more speculative technologies, like cold fusion, to make their numbers.

The new approach — which the United Nations hopes will inform the debate up to the next climate summit in Paris in fall 2015 — could offer a path out of the stalemate that international climate negotiations have become.

No country will commit legally to slash its CO2 emissions by 80 percent over the next 40 years. But if there is a map, many might offer their best effort to follow it. Absent a legal commitment, a long-term path could encourage the large investments ultimately required to address the problem.

“Governments won’t precommit to huge technological revolutions on a legal basis,” Professor Sachs said. “Countries might be willing to aspire more on a conditional basis.”

What’s more, countries are more likely to participate if they understand what everybody else is trying. “The Chinese want to see an American pathway to two degrees,” Mr. Schmidt-Traub said.

Big challenges remain. Any 40-year forecast must be taken with some skepticism. Technologies that seem feasible and economic today might turn out not to be. And it bears repeating that though the teams contend they can get to 1.6 tons per person, they have not yet.

Russia, for instance, hit the target. But Oleg Lugovoy of the Environmental Defense Fund, who worked on the Russian plan, observed that “if we don’t have carbon capture and storage we would have to reconsider.”

And while sketching a technological path toward a low carbon economy will certainly help ground in reality the abstract negotiations over the future of climate, it does not do away with the main hitch that has stumped progress for decades: How much will this all cost and who will pay for it?

The team purposefully did not assess the costs of their paths to prevent distributional arguments from flaring up immediately. That gives policy makers space to consider the implications without having to stake out a negotiating stance.

An assessment of costs and how they could be distributed will be added in a next iteration to be published next spring. Debates over cost allocation and technology transfer could still hamstring prospects of substantive international collaboration.

But despite these risks, the report offers a promising new path to overcome the decades-old logjam of climate change negotiations. For the first time, when we say we can stop the climate from heating we will more or less know what we are talking about.

Email: eporter@nytimes.com;
Twitter: @portereduardo

A version of this article appears in print on , on Page B1 of the New York edition with the headline: Blueprints for Taming the Climate Crisis. Order Reprints | Today’s Paper | Subscribe